1. Field of the Invention
The present invention relates generally to a dual rotor axial-flow rotor valve structure, and more particularly to a dual rotor axial-flow rotor valve structure, which has smaller volume and is convenient to operate.
2. Description of the Related Art
Following the raise of people's music appreciation level, performers have been more and more required to improve their performance skill to satisfy the audiences. On the other hand, the improvements of the structures of the musical instruments help in promoting the skills of the performers.
FIG. 1 shows a musical instrument C (bass trombone) with two tuning slide, assemblies. The musical instrument C mainly includes a main tuning slide assembly 5, a slide tube 50, a first tuning slide assembly 51, a second tuning slide assembly 52, a first rotor valve 53 and a second rotor valve 54. One end of the main tuning slide assembly 5 is a trumpet-shaped end 55. The other end of the main tuning slide assembly 5 is connected to the slide tube 50 and the first and second tuning slide assemblies 51, 52 via the first and second rotor valves 53, 54 respectively. A mouthpiece 501 is disposed at the other end of the slide tube 50. The first and second rotor valves 53, 54 are respectively connected with a first shift rod 531 and a second shift rod 541, which extend outward. In operation, via the first and second shift rods 531, 541, the first and second rotor valves 53, 54 are driven to change the communication relationships between the slide tube 50 and the first and second tuning slide assemblies 51, 52 and the main tuning slide assembly 5 to form different resonance lengths. For example, in the case that the first and second rotor valves 53, 54 are such positioned that the slide tube 50 directly communicates with the main tuning slide assembly 5, the musical instrument will have a shortest resonance length. In the case that the first and second rotor valves 53, 54 are such positioned that the slide tube 50 communicates with the main tuning slide assembly 5 through the first tuning slide assembly 51 or second tuning slide assembly 52, the musical instrument will have a longer resonance length. In the case that the first and second rotor valves 53, 54 are such positioned that the slide tube 50 communicates with the main tuning slide assembly 5 through both the first and second tuning slide assemblies 51, 52, the musical instrument will have a longest resonance length. Accordingly, the musical instrument can have different tunes to achieve different performance effects. However, in practice, the above structure has the following shortcomings:    1. The first and second rotor valves 53, 54 are respectively disposed between the main tuning slide assembly 5, the slide tube 50 and the first and second tuning slide assemblies 51, 52. Therefore, a larger space is occupied. This complicates the loop design of the musical instrument C and increases the development cost of the product. Also, this may affect the sound quality.    2. The first and second rotor valves 53, 54 are separately arranged with each other through a tube to achieve different connection and communication relationships between the loops. As a result, the number of the components is increased to increase the manufacturing cost. Moreover, the structure of the musical instrument C as a whole is complicated. Also, the manufacturing process is more complicated. This is not propitious for the promotion of competitiveness of the product.    3. The musical instrument C has a first rotor valve 53 and a second rotor valve 54 that are independent from each other. Therefore, in maintenance, it is necessary to disassemble the first and second rotor valves 53, 54 one by one. Also, after the maintenance, it is necessary assemble, the first and second rotor valves 53, 54 one by one. This causes inconvenience in use of the musical instrument C.